Chinese schools are teaching young students how to fight off knife-wielding attackers following a string of stabbings aimed at children.

Twenty-seven people have been killed and more than 80 injured since March in a spate of knife attacks that have alarmed the public.

The most recent school attack, on Friday, saw Min Yongjun stab and slash 22 students at a primary school in the central Chinese province of Henan.

No-one died in Friday's violence but the official news agency Xinhua said eight of the children were taken to hospital for surgery for facial wounds.

The previous day, a man wielding a knife injured 15 students and a teacher at a primary school in southern China.

One of the children hurt in Friday's attack talks to her mum on the phone

And on Sunday, a man injured six women with a cleaver in southern China before killing himself by jumping from a building.

With much of the violence taking place on school grounds, there have long been calls for stronger protection for students.

Video:CCTV Of Chinese School Knife Attack

The deaths of children strike an especially deep chord in a country where most urban families are allowed to have only one child, said Yang Dongping, an education expert at the Beijing Institute of Technology.

The attacks also fuelled concerns about the social malaise underneath China's rapid economic growth, as some attackers - usually young men - had recently lost jobs or felt left out of the country's economic boom.

There are also calls for the government to offer more psychological consultations across the country.

Earlier this week police released surveillance footage of Friday's school attack showing the attacker pursuing a group of children through a school gate.

Panicked children stream out of the school gates to escape Min, before adults appear holding straw brooms and chase him out.

Authorities said that Min, 36, had been "influenced by rumours of the end of the world", which some people believe is due to occur on December 21, in line with supposed Mayan prophecies.

The attack happened on the same day that 20 children were shot dead at a US primary school in Connecticut.

Chinese social media users complained that while the US massacre received ample coverage, the Henan attack barely registered with official state media.

"The headlines are still dominated by the American attack, I haven't seen reports about the attack in Henan which happened on the same day," wrote one user of Sina Weibo - a website similar to Twitter.

"Aren't Chinese children's lives also important? It's a tragedy."

Another user said: "On the same day as the US shooting, 22 children were slashed at the school in Henan, but mainstream media were virtually mute on this. Are the lives of Chinese children worthless to them?"

According to instructions obtained by the China Digital Times - a website following social and political developments in China and run by the University of California - the government's central propaganda department told Chinese media to play down the Henan attack.

It quoted officials as telling media not to put the news on the front page or lure readers to it, and not to produce reports or comment on it other than those provided by Xinhua.

Criticism of official media coverage follows the installation last month of a new Communist Party chief, Xi Jinping, who has told the media not to shy away from focusing on genuine news.